1. Technical Field
The present application relates to reel systems for the receiving, storage, and deploying of cables (such as one or more electrical lines), hoses, umbilical connections (such as bundles of hydraulic lines, electrical lines, cables, hoses, and/or combinations thereof) and the like.
2. Related Art
Subsea blowout prevention equipment (BOP) uses large, specialized valves or similar mechanical devices, usually installed redundantly in stacks, to seal, control and monitor oil and gas wells. Redundant sub-sea control pods are used to control the valves of the BOP stack, some of which are referred to in the industry as blue and yellow pods. The pods of the BOP stack are controlled by cables, hoses, umbilical connections and the like with various capacity outside diameters. The reel systems used for winding the cable, hoses, umbilical connections and the like onto spools, particularly on off-shore drill rigs, employ spools which are mechanically driven.
Off-shore drill rigs often use multiplex cable reels, hot line hose reels, riser fill valve hose reels and the like in control systems for BOP equipment. Each of these components may provide various functionalities. In a typical rig, four spools may provide control cables for a BOP stack. These components may function as follows: multiplex cable reel assemblies may be used to pay out and retrieve multiplex cables that may be used to transmit electric signals to allow for the control of sub-sea hydraulic functions on the sub-sea blue and yellow pods; a hot line hose reel assembly may be used to pay out and retrieve a hose that provides hydraulic fluid from the drilling rig deck to the sub-sea pods to allow for the control of sub-sea hydraulic functions on the sub-sea blue and yellow pods; and a riser fill valve hose reel assembly may pay out and retrieve a hose that provides, in response to a sudden pressure differential between the inside and outside of a riser opens to allow the riser to fill with seawater and thus equalizing the pressure differential and preventing collapse of the riser.
In operation, the spools are typically located on the drillship near a moon pool area (i.e. the opening in the floor or base of the platform to provide access to the water below) and may be on different levels depending on the rig design. The cable or hose often is deployed from the spool to an overhead roller type turn down sheave, or multiple sheaves, to direct the cable or hose to the blue and yellow pods on the BOP stack assembly in the drill ship's moon pool.
Typical systems employ manual, pneumatically-controlled, mechanical control systems for each of the individual reel assemblies, to position the sub-sea end of the cable or hose to the pod. Once the cables and hoses are connected to the pods, the operation of deploying the BOP stack begins. Drill pipe and flotation risers having typical lengths of 60 to 90 feet or more (nominally, about 18 to 28 meters) are attached to the stack. The cables and hoses are attached to clamps located on the riser as the 60 or 90 foot (nominally, about 18 to 28 meters) sections are made up. The reels are not rotating while the drill pipe and riser sections are made up. Once made up, the reels begin rotating to deploy the cables and hoses until the next section is ready to be attached. This operation continues until the BOP stack is anchored to the sea bed floor. A control stand may be located away from the spools, in the moon pool area, with a clear vision of the deployment. The operator at the remote control stand may be able to operate one or more of the reel assemblies and may make adjustments as may be necessary during the operation.
Currently, the pneumatically driven mechanical control systems used to control the reel assembly operation suffer from various shortcomings. For example, there are limitations on the locations of reel assemblies and a remote control stand because pneumatic control signals are subject to decreasing performance such as slower responses as the distance between the reel and the remote control stand increases. As another example, mechanical push-pull valves are used to alternate control between a local controller and a remote control stand. The use of these valves necessitate that an operator manually activate the valve at each reel assembly to provide full control of the system to the remote control stand. In addition, current reel assemblies do not provide much feedback to the operator about the actual conditions of the cable/hose, such as accurate information about the actual tension on the cable/hose or how much of the cable/hose has been deployed.
Accordingly, a need has long existed for improved systems and methods for controlling cable spooling systems.